| 摘要 |
A low alloy steel, characterized by consisting of, by mass %, C:0.2-0.55%, Si:0.05-0.5%, Mn:0.1-1%, S:0.0005-0.01%, O(Oxygen):0.0010-0.01%, Al:0.005-0.05%, Ca:0.0003-0.007%, Ti:0.005-0.05%, Cr:0.1-1.5%, Mo:0.1-1% and Nb:0.005-0.1%, and the balance Fe and impurities; and also characterized by the impurities whose contents are restricted to P </= 0.03% and N </= 0.015%; and further characterized by containing composites of inclusions of not greater than 7 mu m in major axis with appearance frequency of not less than 10 pieces of composites per 0.1mm<2> of the steel cross section, wherein the composite comprises an outer shell of carbonitride of Ti and/or Nb surrounding a nucleus of oxysulfide of Al and Ca. <??>The low alloy steel suppresses pitting caused by inclusions and suppresses SSC induced by pitting. |
